Abstract:Abstract:The three-dimensional model of the CtCBM35 (Cthe 2811), i.e. the family 35 carbohydrate binding module (CBM) from the Clostridium thermocellum family 26 glycoside hydrolase (GH) β-mannanase, generated by Modeller9v8 displayed predominance of β-sheets arranged as β-sandwich fold. Multiple sequence alignment of CtCBM35 with other CBM35s showed a conserved signature sequence motif Trp-Gly-Tyr, which is probably a specific determinant for mannan binding. Cloned
“…1 ). Trp57 and Lys60 in Man1ECBM corresponded to Tyr80 and Lys83 in CtCBM35, and Tyr60 and Lys63 in PaCBM35, which have been proven to participate in the substrate binding [ 36 ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…1). According to the literature [36], there is a hydrophobic platform, which consists of three aromatic amino acid residues Phe,Trp and Trp, participating in substrate binding. In CtCBM35 and PaCBM35 (PDB ID: 2BGO), these three residues are Phe100, Trp129,Try131, and Phe87,Trp117, Trp119, respectively.…”
Section: Cloning and Sequence Analysis Of β-Mannanase Genementioning
confidence: 99%
“…Through the analysis for multiple sequence alignment, the characteristic sequence, "Trp-Gly-Tyr (WGY)" motif, was found in Man1ECBM. The WGY motif, which may determine the specificity of mannose binding, consists generally in CBM35 and CBM6 [36]. The Tyrosine residue at the third position of WGY motif is relatively conservative, which can be replaced with Trp or Phe.…”
Section: Cloning and Sequence Analysis Of β-Mannanase Genementioning
Background: β-mannanase can hydrolyze β-1,4 glycosidic bond of mannan by the manner of endoglycosidase to generate mannan-oligosaccharides. Currently, β-mannanase has been widely applied in food, medicine, textile, paper and petroleum exploitation industries. β-mannanase is widespread in various organisms, however, microorganisms are the main source of β-mannanases. Microbial β-mannanases display wider pH range, temperature range and better thermostability, acid and alkali resistance, and substrate specificity than those from animals and plants. Therefore microbial β-mannanases are highly valued by researchers. Recombinant bacteria constructed by gene engineering and modified by protein engineering have been widely applied to produce β-mannanase, which shows more advantages than traditional microbial fermentation in various aspects. Results: A β-mannanase gene (Man1E), which encoded 731 amino acid residues, was cloned from Enterobacter aerogenes. Man1E was classified as Glycoside Hydrolase family 1. The bSiteFinder prediction showed that there were eight essential residues in the catalytic center of Man1E as Trp166, Trp168, Asn229, Glu230, Tyr281, Glu309, Trp341 and Lys374. The catalytic module and carbohydrate binding module (CBM) of Man1E were homologously modeled. Superposition analysis and molecular docking revealed the residues located in the catalytic module of Man1E and the CBM of Man1E. The recombinant enzyme was successfully expressed, purified, and detected about 82.5 kDa by SDS-PAGE. The optimal reaction condition was 55 °C and pH 6.5. The enzyme exhibited high stability below 60 °C, and in the range of pH 3.5-8.5. The β-mannanase activity was activated by low concentration of Co 2+ , Mn 2+ , Zn 2+ , Ba 2+ and Ca 2+. Man1E showed the highest affinity for Locust bean gum (LBG). The K m and V max values for LBG were 3.09 ± 0.16 mg/mL and 909.10 ± 3.85 μmol/(mL min), respectively. Conclusions: A new type of β-mannanase with high activity from E. aerogenes is heterologously expressed and characterized. The enzyme belongs to an unreported β-mannanase family (CH1 family). It displays good pH and temperature features and excellent catalysis capacity for LBG and KGM. This study lays the foundation for future application and molecular modification to improve its catalytic efficiency and substrate specificity.
“…1 ). Trp57 and Lys60 in Man1ECBM corresponded to Tyr80 and Lys83 in CtCBM35, and Tyr60 and Lys63 in PaCBM35, which have been proven to participate in the substrate binding [ 36 ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…1). According to the literature [36], there is a hydrophobic platform, which consists of three aromatic amino acid residues Phe,Trp and Trp, participating in substrate binding. In CtCBM35 and PaCBM35 (PDB ID: 2BGO), these three residues are Phe100, Trp129,Try131, and Phe87,Trp117, Trp119, respectively.…”
Section: Cloning and Sequence Analysis Of β-Mannanase Genementioning
confidence: 99%
“…Through the analysis for multiple sequence alignment, the characteristic sequence, "Trp-Gly-Tyr (WGY)" motif, was found in Man1ECBM. The WGY motif, which may determine the specificity of mannose binding, consists generally in CBM35 and CBM6 [36]. The Tyrosine residue at the third position of WGY motif is relatively conservative, which can be replaced with Trp or Phe.…”
Section: Cloning and Sequence Analysis Of β-Mannanase Genementioning
Background: β-mannanase can hydrolyze β-1,4 glycosidic bond of mannan by the manner of endoglycosidase to generate mannan-oligosaccharides. Currently, β-mannanase has been widely applied in food, medicine, textile, paper and petroleum exploitation industries. β-mannanase is widespread in various organisms, however, microorganisms are the main source of β-mannanases. Microbial β-mannanases display wider pH range, temperature range and better thermostability, acid and alkali resistance, and substrate specificity than those from animals and plants. Therefore microbial β-mannanases are highly valued by researchers. Recombinant bacteria constructed by gene engineering and modified by protein engineering have been widely applied to produce β-mannanase, which shows more advantages than traditional microbial fermentation in various aspects. Results: A β-mannanase gene (Man1E), which encoded 731 amino acid residues, was cloned from Enterobacter aerogenes. Man1E was classified as Glycoside Hydrolase family 1. The bSiteFinder prediction showed that there were eight essential residues in the catalytic center of Man1E as Trp166, Trp168, Asn229, Glu230, Tyr281, Glu309, Trp341 and Lys374. The catalytic module and carbohydrate binding module (CBM) of Man1E were homologously modeled. Superposition analysis and molecular docking revealed the residues located in the catalytic module of Man1E and the CBM of Man1E. The recombinant enzyme was successfully expressed, purified, and detected about 82.5 kDa by SDS-PAGE. The optimal reaction condition was 55 °C and pH 6.5. The enzyme exhibited high stability below 60 °C, and in the range of pH 3.5-8.5. The β-mannanase activity was activated by low concentration of Co 2+ , Mn 2+ , Zn 2+ , Ba 2+ and Ca 2+. Man1E showed the highest affinity for Locust bean gum (LBG). The K m and V max values for LBG were 3.09 ± 0.16 mg/mL and 909.10 ± 3.85 μmol/(mL min), respectively. Conclusions: A new type of β-mannanase with high activity from E. aerogenes is heterologously expressed and characterized. The enzyme belongs to an unreported β-mannanase family (CH1 family). It displays good pH and temperature features and excellent catalysis capacity for LBG and KGM. This study lays the foundation for future application and molecular modification to improve its catalytic efficiency and substrate specificity.
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